Online content may be received from various first-party or third-party sources. In general, first-party content refers to the primary online content requested or displayed by the client device. For example, first-party content may be a webpage requested by the client or a stand-alone application (e.g., a video game, a chat program, etc.) running on the device. Third-party content, in contrast, refers to additional content that may be provided in conjunction with the first-party content. For example, third-party content may be a public service announcement or advertisement that appears in conjunction with a requested webpage (e.g., a search result webpage from a search engine, a webpage that includes an online article, a webpage of a social networking service, etc.) or within a stand-alone application (e.g., an advertisement within a game). More generally, a first-party content provider may be any content provider that allows another content provider (i.e., a third-party content provider) to provide content in conjunction with that of the first-party.
In some cases, third-party content may be selected for presentation with first-party content based on the results of a content auction. For example, third-party content providers may place bids in a content auction to compete for the ability to provide an advertisement with first-party content. The third-party content providers may also have disparate goals in mind when placing content auction bids. For example, a provider of a public service message may wish to maximize exposure of the public service message to users. In contrast, an online retailer may wish to maximize the number of times that an advertisement is presented with first-party content and leads to an online sale. However, it is challenging and difficult to develop systems that determine an auction bid on behalf of a third-party content provider that achieves a specified goal of the content provider.